On Thu, 2008-07-03 at 17:33 +1000, Paul Mackerras wrote:
> Dave Kleikamp writes:
>
> > This patch defines:
> >
> > - PROT_SAO, which is passed into mmap() and mprotect() in the prot field
> > - VM_SAO in vma->vm_flags, and
> > - _PAGE_SAO, the combination of WIMG bits in the pte that enables strong
> > access ordering for the page.
> >
> > NOTE: There doesn't seem to be a precedent for architecture-dependent
> > vm_flags.
> > It may be better to define VM_SAO somewhere in include/asm-powerpc/. Since
> > vm_flags is a long, defining it in the high-order word would help prevent a
> > collision with any newly added values in architecture-independent code.
>
> This puts _PAGE_SAO in pgtable-ppc64.h, which is fine, but then your
> patch 4/5 breaks the build for 32-bit machines with an error like
> this:
>
> In file included from /home/paulus/kernel/powerpc/include/linux/mman.h:4,
> from
> /home/paulus/kernel/powerpc/arch/powerpc/kernel/asm-offsets.c:22:
> include2/asm/mman.h: In function ?arch_vm_get_page_prot?:
> include2/asm/mman.h:43: error: ?_PAGE_SAO? undeclared (first use in this
> function)
> include2/asm/mman.h:43: error: (Each undeclared identifier is reported only
> once
> include2/asm/mman.h:43: error: for each function it appears in.)
> make[2]: *** [arch/powerpc/kernel/asm-offsets.s] Error 1
>
> because of course we don't have a definition of _PAGE_SAO for 32-bit
> machines...
>
> Could you fix it and re-send please?
Sorry. Here's a replacement for patch 4/5. It adds an #ifdef
CONFIG_PPC64 around the new code.
The alternative would be to introduce mman_ppc64.h which I think would
be overkill.
powerpc: Add Strong Access Ordering
Allow an application to enable Strong Access Ordering on specific pages of
memory on Power 7 hardware. Currently, power has a weaker memory model than
x86. Implementing a stronger memory model allows an emulator to more
efficiently translate x86 code into power code, resulting in faster code
execution.
On Power 7 hardware, storing 0b1110 in the WIMG bits of the hpte enables
strong access ordering mode for the memory page. This patchset allows a
user to specify which pages are thus enabled by passing a new protection
bit through mmap() and mprotect(). I have tentatively defined this bit,
PROT_SAO, as 0x10.
Signed-off-by: Dave Kleikamp <[EMAIL PROTECTED]>
---
arch/powerpc/kernel/syscalls.c | 3 +++
include/asm-powerpc/mman.h | 30 ++++++++++++++++++++++++++++++
2 files changed, 33 insertions(+)
Index: b/arch/powerpc/kernel/syscalls.c
===================================================================
--- a/arch/powerpc/kernel/syscalls.c
+++ b/arch/powerpc/kernel/syscalls.c
@@ -143,6 +143,9 @@
struct file * file = NULL;
unsigned long ret = -EINVAL;
+ if (!arch_validate_prot(prot))
+ goto out;
+
if (shift) {
if (off & ((1 << shift) - 1))
goto out;
Index: b/include/asm-powerpc/mman.h
===================================================================
--- a/include/asm-powerpc/mman.h
+++ b/include/asm-powerpc/mman.h
@@ -1,7 +1,9 @@
#ifndef _ASM_POWERPC_MMAN_H
#define _ASM_POWERPC_MMAN_H
+#include <asm/cputable.h>
#include <asm-generic/mman.h>
+#include <linux/mm.h>
/*
* This program is free software; you can redistribute it and/or
@@ -26,4 +28,32 @@
#define MAP_POPULATE 0x8000 /* populate (prefault) pagetables */
#define MAP_NONBLOCK 0x10000 /* do not block on IO */
+#ifdef CONFIG_PPC64
+/*
+ * This file is included by linux/mman.h, so we can't use cacl_vm_prot_bits()
+ * here. How important is the optimization?
+ */
+static inline unsigned long arch_calc_vm_prot_bits(unsigned long prot)
+{
+ return (prot & PROT_SAO) ? VM_SAO : 0;
+}
+#define arch_calc_vm_prot_bits(prot) arch_calc_vm_prot_bits(prot)
+
+static inline pgprot_t arch_vm_get_page_prot(unsigned long vm_flags)
+{
+ return (vm_flags & VM_SAO) ? __pgprot(_PAGE_SAO) : 0;
+}
+#define arch_vm_get_page_prot(vm_flags) arch_vm_get_page_prot(vm_flags)
+
+static inline int arch_validate_prot(unsigned long prot)
+{
+ if (prot & ~(PROT_READ | PROT_WRITE | PROT_EXEC | PROT_SEM | PROT_SAO))
+ return 0;
+ if ((prot & PROT_SAO) && !cpu_has_feature(CPU_FTR_SAO))
+ return 0;
+ return 1;
+}
+#define arch_validate_prot(prot) arch_validate_prot(prot)
+
+#endif /* CONFIG_PPC64 */
#endif /* _ASM_POWERPC_MMAN_H */
--
David Kleikamp
IBM Linux Technology Center
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